Conventional toilets typically employ a generally rectangular porcelain tank mounted immediately above a porcelain bowl from which a quantity of water is rapidly drained in order to flush waste from the bowl into the sewer system. One very common design uses a flapper valve made of an elastomeric material that normally covers the drain outlet of the tank. When the flush handle on the outside of the tank is manually depressed the flapper valve is lifted and the head of water in the tank drains through the drain outlet into the bowl, thereby flushing the contents of the bowl into the sewer system. The flapper valve is designed with an inverted air chamber so that it initially floats as it is lifted away from the drain outlet in the bottom of the tank. This allows sufficient flushing water to flow into the bowl even if the user immediately releases the flush handle. When the water level in the tank drops, the tank is automatically refilled through a fill valve connected to a high pressure water supply line.
The typical fill valve for the tank comprises a ballcock or pilot fill valve mounted in the tank on top of a riser which extends through an opening in the bottom of the tank and is connected to a pressurized water line in the house. When the tank drains, a float connected to the ballcock or pilot fill valve descends. This activates the ballcock or pilot fill valve and it begins to refill the tank with water at a rate much slower than the rate at which water flows through the drain outlet. When the tank is nearly empty, the flapper valve closes. The tank continues to refill as the float connected to the ballcock or pilot fill valve rises. At the same time water from the ballcock or pilot fill valve enters an overflow tube and refills the bowl to the normal standing water level to provide a trap seal. Once the float reaches a predetermined height indicating that the tank is full, the ballcock or pilot fill valve completely turns off.
The foregoing general conventional arrangement is still widely used today but has been modified in recent years with new designs to meet low volume (1.6 gal.) flush toilets required by regulations in many jurisdictions. One pilot fill valve construction that was devised by one of these inventors and that has achieved wide market acceptance and success is disclosed in U.S. Pat. No. 6,003,541 entitled “Unitary Float and Arm for Float Operated Valve.” Other fill valves of related construction include U.S. Pat. No. 5,975,125 entitled “Combined Filter and Noise Suppressor for Fill Valve;” U.S. Pat. No. 5,836,346 entitled “Pilot Operated Diaphragm Fill Valve;” and U.S. Pat. No. 5,715,859 entitled “Adjustable Fill Valve Assembly.”
Fill valves made in accordance with this construction include a riser assembly, a valve housing mounted on an upper end of the riser assembly, and a pilot operated diaphragm valve mounted in the valve housing. A float housing is connected to the valve housing. A float arm of a combination float and float arm has a first end pivotally connected to the valve housing for opening and closing a pilot orifice in the diaphragm valve. A second end of the float arm is connected to the float. The float is located in the float housing which has an inlet opening for allowing water to spill into the float housing so that the float rises upwardly and the first end of the float arm fully seals off the pilot orifice. A snap-off cover member extends over and is releasably attached to the valve housing and the float housing.
One limitation of the fill valve construction discussed above is that there is no ability for the fill valve to seal off the pilot orifice in situations where a catastrophic leak in the flush valve assembly or other tank orifice results in the tank being unable to refill itself. That is, the water entering the tank is leaving the tank at a rate such that the water level does not rise to the point that it allows the float that is contained within the float housing to seal off the pilot orifice. In this mode, the fill valve could continue to allow water to run into the tank with the result that this water is simply running back out of the tank and is wasted. A similar limitation of the fill valve construction discussed above is that there is no ability to shut off the fill valve in situations where a slow leak exists in the flush valve due to wear of the flush valve, improper seating, or some other minor malfunction of the flush valve assembly. In this mode, the tank will very slowly leak water through the flush valve assembly and require intermittent functioning of the fill valve to compensate for this slow leak condition, wasting a potentially large amount of water over time.
Accordingly, it is desirable that an improved fill valve assembly be available to overcome the above-mentioned limitations. It is also desirable that the improved fill valve assembly be used as a replacement for fill valves of current manufacture, thus making it available as either an OEM or an after-market product.